principles of inheritance Flashcards
characters inherited by offsprings from parents is called……
inheritance
differences between progeny and parents is called
variation
who were the 3 scientists that rediscovered Mendel’s work
de vrie
Correns
tschermak
specific physical location of a gene or other DNA sequence on a chromosome
locus
basic physical and functional unit of heredity
gene
slightly variable forms of a gene
allele
physical traits
phenotype
genetic makeup
genotype
traits studied by mendel
G for green fruit color.. R for round seed shape.. A for axial flower position V for violet flower color.. I for inflated pod shape.. T for tall plant height.. Y for yellow seed color..
state first law of inheritance/ law of dominance
characters are controlled by factors/ genes
factors occur in pair
incase of dissimilar factors, one factor dominates the other
what is test cross
mating w recessive parent to determine the genetic makeup
when dominant allele does not express the dominant characters fully in heterozygous condition
incomplete dominance
it is an exception to Mendel’s 1st law
when both alleles express themselves fully
codominance
eg- human blood grp
more than 2 alleles of a gene in a population
multiple alleles
state second law of inheritance/ law of segregation/ law of purity of gametes
during gamete formation the 2 alleles of a gene must segregate to move into different gametes
state third law of inheritance/ law of assortment
alleles of genes located on different chromosomes assort independently of each other
what is linkage (exception of third law)
when 2 genes are situated on same chromosome and they are situated closely to each other then both the alleles on one chromosome are passed together in the gamete
linkage is inversely proportional to
distance between genes
which insect did T.H. Morgan choose
drosophila melanogaster (fruit fly)
reasons for which th morgan chose drosophila melanogaster
has contrasting traits
2 week lifecycle
grows easily in lab
male and female are morphologically distinct
change in quality or quantity of genetic material
mutation
anything which causes mutation
mutagens (physical/ chemical)
types of mutation
genomatic- number
chromosomal- structure
gene
types of genomatic mutation
polyploidy- repetition of haploid set
aneuploidy- loss or gain of 1 or few chromosomes
what does colchicine do
stops the formation of spindle fibers in metaphase
types of aneuploidy
monosomic- turner syndrome (-1)
nullisomic (-2)
trisomic- down syndrome (+1)
tetrasomic (+2)
types of chromosomal mutation
intrachromosomal
interchromosomal
types of intrachromosomal mutation
deficiency- loss of terminal part
deletion- loss of mid part
inversion-
types of interchromosomal mutation
insertion
translocation
types of gene mutation
point
frameshift
types of point mutation
transversion- purine is replaced by pyridine or vice versa
transition- when purine is replaced by purine…..
sickle cell anemia is caused by
point mutation (transversion)
types of male and female heterogamety
MALE- xo type (insects) xx-xy type (humans, drosophilla) FEMALE- zz-zw type
what is parthenogenesis
a form of reproduction in which an egg can develop into an embryo without being fertilized by a sperm
male- arrhenotoky (honeybees)
female- thelytoky
types of genetic disorder
mendelian- caused due to mutation of a single gene
chromosomal- caused due to absence or excess of abnormal chromosomes
types of mendelian disorders
autosomal
sex linked
list 2 x linked disorders
color blindness
hemophilia
what type of disorder is sickle cell anemia
autosomal
an inherited disorder that increases the levels of a substance called phenylalanine in the blood
phenylketonuria
2 types of thalassemia
α thalassemia (ch16)
β thalassemia (ch11)
list recessive autosomal disorders
sickle cell anemia
phenylketonuria
thalassemia
cystic fibrosis
what happens in cystic fibrosis
excess mucus produced
name a dominant autosomal disorder
myotonic dystrophy
list chromosomal disorders
Klinefelter’s syndrome- XXY
turner’s syndrome- completely or partially missing X chromosome
down syndrome- condition in which a child is born with an extra copy of their 21st chromosome (not sterile)
what is pedigree
it is a family tree in which we observe the passing of a particular trait from 1 generation to another
